Fatbergs – enormous solid masses of oil, grease, wet wipes and other hygiene products that congeal together to cause major blockages – are wreaking havoc on the sewers of cities around the world. A 130 tonne specimen described as a “monster” recently caused backups in sewers in London’s Whitechapel, and the cities of Baltimore, Singapore and Dannevirke, New Zealand have also all experienced similar issues in recent weeks.